Two-stage treatment of infected total knee arthroplasty: two to thirteen year experience using an articulating preformed spacer

Infection following knee replacement is an important cause of failure despite rigorous prophylaxis antibiotic protocols. The two-stage reimplantation procedure is considered the gold standard for treatment of subacute and chronic deep periprosthetic infections. The purpose of this study was to determine whether or not a preformed articulated spacer would allow comparable eradication of infection equal to rates reported in published studies and to see whether there is a resulting improvement in postoperative function with an acceptable quality of life, reducing postoperative pain and limiting surgical complications, thus simplifying the second stage of the procedure.

We retrospectively reviewed 50 patients with infected TKA who underwent a two-stage exchange arthroplasty using an articulating preformed spacer. The device, designed like an ultracongruent condylar knee prosthesis, is composed of acrylic cement impregnated with antibiotic, with tested and standardised mechanical properties and antibiotic content and release mechanism.

The median follow-up period was seven (two to 13) years. Two-stage exchange arthroplasty was successful in controlling the infection in 92% of patients; 64% of patients where women, and median patient age was 68 (54-80) years. Median implantation time of the preformed spacer was 16 (four to 60) weeks; 4% of infections were delayed, and 96% were late. Forty-six percent were caused by coagulase-negative Staphylococcus (CoNS). Mean Knee Society Score (KSS) was 35.38 (clinical) and 37.96 (function) on presentation; it improved to a mean of 72.92 (clinical) and 76.04 (function) after the first stage and to a mean of 75.38 (clinical) and 80.58 (function) at the final review. Bone loss was unchanged between stages, and range of motion remained unchanged or improved after definitive reimplantation.

The use of preformed articulated knee spacer during a two stage technique for infected TKA improves patient QOL between stages and increases patient compliance and cooperation, reducing social costs.